Laser diode array

ABSTRACT

A process of making a laser diode device includes these steps: applying a bonding layer such as molybdenum manganese to surfaces of first and second bodies of dielectric material such as beryllium oxide; joining the first and second bodies together to form a cavity; and bonding a sectored conductor ring to the bonding layer within the cavity. 
     The laser diode device made by the process includes a body of dielectric material such as beryllium oxide forming a cavity; a bonding layer lining the cavity; a conductor bonded to the layer within the cavity; the conductor being divided into ring sectors separated by radial diode bar spaces; and a laser diode bar in each of the bar spaces forming an array of such laser diode bars. The ring sectors and laser diode bars together form a series path for electric current around the conductor to energize the laser diode bars.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a laser diodes mounted in an array,surrounding a laser medium for excitation thereof, and particularly tothe fabrication and structure of the surrounding array.

2. Background Information and Disclosure

Excitation of a laser medium from an adjacent or surrounding array oflaser diodes is known in the prior art.

U.S. Pat. No. 5,033,058 to Cabaret et al discloses a laser rod in aglass tube with a segmented reflective coating. Laser diodes placedaround the glass tube emit through windows in the reflective coating toexcite the laser rod.

U.S. Pat. No. 5,040,187 to Karpinski, and U.S. Pat. No. 5,128,951 toKarpinski both disclose flat laser diode arrays mounted in a ceramicsubstrate with a metallized surface. Current through the metallizedsurface energizes the laser diodes, which then excite an adjacent lasermedium, not shown in the patents.

U.S. Pat. No. 5,521,936 to Irwin discloses a radial array of laserdiodes mounted in a sectored conductive ring surrounding a laser rod. Aninner tube forms a coolant channel around the laser rod, and an outersleeve forms a coolant channel around the ring and the laser diodes.

The most relevant prior art that I know of is U.S. Pat. No. 5,627,850 toIrwin et al. It discloses a laser diode array which includes adielectric block with a conductor layer “direct bonded” to it. Theconductor layer is divided into sectors by spaced diode bar spaces. Alaser diode bar is positioned in each space. The conductor layer andlaser diode bars together surround a laser medium which is excited bythe laser diode bars.

SUMMARY OF THE INVENTION

This invention is a laser diode device, and a process of making it. Theprocess includes these steps: applying a bonding layer such asmolybdenum manganese to surfaces of first and second bodies ofdielectric material such as beryllium oxide; joining the first andsecond bodies together to form a cavity; and bonding a sectoredconductor ring to the bonding layer within the cavity.

The device includes a body of dielectric material such as berylliumoxide forming a cavity; a bonding layer lining the cavity; a conductorbonded to the layer within the cavity; the conductor being divided intoring sectors separated by radial diode bar spaces; and a laser diode barin each of the bar spaces forming an array of such laser diode bars. Thering sectors and laser diode bars together form a series path forelectric current around the conductor to energize the laser diode bars.

DRAWING

FIGS. 1-6 are cross-sectional views of various stages of fabrication ofa laser and diode array according to this invention.

DESCRIPTION

The following is a description of the fabrication of a laser diode arrayaccording to this invention.

FIG. 1 shows a lower block 10 of dielectric material, preferablyberyllium oxide (BeO). The block 10 includes a cavity 11 which issemi-cylindrical in the example shown.

FIG. 2 shows the semi-cylindrical cavity lined with a layer of bondingmaterial 12, preferably molybdenum manganese (MoMn). The bonding layer12 is a metalized coating applied by painting, spraying, sintering, orscreen printing on the BeO surface.

FIG. 3 shows a conductor ring 13 mounted in the semi-cylindrical cavityof the lower block 10, and bonded to its bonding layer 12, preferably bycopper-silver solder. An upper block 10, similar to the lower block andinverted relative to it, is mounted over the conductor ring 13 which isthen is similarly bonded to the upper block 10.

FIG. 4 shows the conductor ring 13 including a number of radial diodebar spaces 21, dividing the ring 13 into a plurality of ring sectors 20a, 20 b, 20 c, etc. (see also FIG. 5). The diode bar spaces 21 may beexpanded at their radial inner and outer ends 22, 23. The ring sectorsmay each include a stress relief groove 24.

FIG. 5 shows a laser diode bar 25 mounted in each bar space 21, acoolant tube 16 of a dielectric material mounted within the conductorring 13, and a laser medium 26 mounted and centered within the coolanttube 16, whereby laser and tube together form an annular coolant flowchannel 18 around the laser medium 26. The channel 18 is a conduit forwater to remove heat from the laser medium 26. The laser diode bars 25are held in the bar spaces 21, preferably by solder. The ring sectors 20and laser diode bars 25 mounted between them together form a series pathfor electric current around the conductor ring 13.

FIG. 6 shows the device of FIG. 5 in operation. With electric currentthrough successive ring sectors 20 and laser diodes 25 mounted betweenthem, the laser diodes 25 emit light which in turn energizes the lasermedium 26. FIG. 6 also shows the symmetry of pumping action produced bythe array of laser diodes.

The bonding layer 12 between the dielectric blocks 10 and the conductorring 13 is an improvement over the “direct bond copper” techniquedisclosed in U.S. Pat. No. 5,627,850, discussed above. The bonding layer12 forms a stronger, more reliable bond with the BeO blocks.

In the devices described, the conductor ring 13 is preferably copperbecause of its thermal and electrical conductivity, and the blocks 10are preferably beryllium oxide because it is a thermally conductivedielectric. Some other ceramic or oxide such as alumina could be used,for example in a configuration where thermal conductivity of the blockis not so important.

The foregoing description of a preferred embodiment of this inventionsets forth the best mode contemplated by the inventor of carrying outthis invention. Specific details as to materials, quantities,dimensions, and the like are intended as illustrative and not limiting,except as limited by the following claims. The concept and scope of theinvention are limited only by the following claims and equivalentsthereof.

What is claimed is:
 1. A laser diode device, including: lower and upperblocks of dielectric material, each said block defining asemi-cylindrical cavity; a bonding layer of molybdenum manganese liningeach said cavity, each said layer being of macroscopic thickness; saidupper block inverted relative to said lower block and mounted thereon todefine therewith a cylindrical cavity; a cylindrical copper ringdisposed within said cylindrical cavity and bonded to said bondinglayers of said lower and upper blocks, said copper ring including aplurality of separate ring sectors with radial diode bar spaces betweenadjacent sectors, the copper of said ring being of a thicknesssubstantially greater than the thickness of said bonding layers; and alaser diode bar disposed in each of said bar spaces in a circumferentialarray of said laser diode bars; said ring sectors and said laser diodebars together forming a series path for electric current around saidcopper ring to energize said laser diode bars.
 2. A laser diode deviceas defined in claim 1, in which said dielectric material is berylliumoxide.
 3. A laser diode device as defined in claim 1, in which saidcopper ring is bonded to said bonding layers by copper-silver solder.